docs: def addAttachment(self, oid, file_path):
          """ Adds an attachment to a feature service
              Input:
                oid - string - OBJECTID value to add attachment to
                file_path - string - path to file
              Output:
                JSON Repsonse
          """
          if self.hasAttachments == True:
              attachURL = self._url + "/%s/addAttachment" % oid
              params = {'f':'json'}
              parsed = urlparse.urlparse(attachURL)
  
              files = {'attachment': file_path}
              res = self._post(url=attachURL,
                               param_dict=params,
                               files=files,
                               securityHandler=self._securityHandler,
                               proxy_port=self._proxy_port,
                               proxy_url=self._proxy_url)
              return self._unicode_convert(res)
          else:
              return "Attachments are not supported for this feature service."